import XLSX from 'xlsx'
import FileSaver from 'file-saver'


// function sheetToBlob(sheet, sheetName) {
//     sheetName = sheetName || 'sheet1';
//     let workbook = XLSX.utils.book_new()
//     workbook.SheetNames[0] = sheetName
//     workbook.Sheets[sheetName] = sheet;
//     let wopts = {
//         bookType: 'xlsx',
//         bookSST: false,
//         type: 'binary'
//     }
//     let wbout = XLSX.write(workbook, wopts);
//     let blob = new Blob([this.strToArrayBuffer(wbout)], {type: "application/octet-stream"})
//
//     FileSaver.saveAs(blob, "电子化移交单.xlsx")
//
// }
//
// function strToArrayBuffer(str) {
//     let buf = new ArrayBuffer(str.length);
//     let view = new Uint8Array(buf);
//     for (let i = 0; i != str.length; ++i) view[i] = str.charCodeAt(i) & 0xFF;
//     return buf;
// }


function generateArray(table) {
    let out = [];
    let rows = table.querySelectorAll('tr');
    let ranges = [];
    for (let R = 0; R < rows.length; ++R) {
        let outRow = [];
        let row = rows[R];
        let columns = row.querySelectorAll('td');
        for (let C = 0; C < columns.length; ++C) {
            let cell = columns[C];
            let colspan = cell.getAttribute('colspan');
            let rowspan = cell.getAttribute('rowspan');
            let cellValue = cell.innerText;
            if (cellValue !== "" && cellValue == +cellValue) cellValue = +cellValue;

            //Skip ranges
            ranges.forEach(function (range) {
                if (R >= range.s.r && R <= range.e.r && outRow.length >= range.s.c && outRow.length <= range.e.c) {
                    for (let i = 0; i <= range.e.c - range.s.c; ++i) outRow.push(null);
                }
            });

            //Handle Row Span
            if (rowspan || colspan) {
                rowspan = rowspan || 1;
                colspan = colspan || 1;
                ranges.push({s: {r: R, c: outRow.length}, e: {r: R + rowspan - 1, c: outRow.length + colspan - 1}});
            }


            //Handle Value
            outRow.push(cellValue !== "" ? cellValue : null);

            //Handle Colspan
            if (colspan) for (let k = 0; k < colspan - 1; ++k) outRow.push(null);
        }
        out.push(outRow);
    }
    return [out, ranges];
}

function datenum(v, date1904) {
    if (date1904) v += 1462;
    let epoch = Date.parse(v);
    return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000);
}

function sheet_from_array_of_arrays(data) {
    let ws = {};
    let range = {s: {c: 10000000, r: 10000000}, e: {c: 0, r: 0}};
    for (let R = 0; R != data.length; ++R) {
        for (let C = 0; C != data[R].length; ++C) {
            if (range.s.r > R) range.s.r = R;
            if (range.s.c > C) range.s.c = C;
            if (range.e.r < R) range.e.r = R;
            if (range.e.c < C) range.e.c = C;
            let cell = {v: data[R][C]};
            if (cell.v == null) continue;
            let cell_ref = XLSX.utils.encode_cell({c: C, r: R});

            if (typeof cell.v === 'number') cell.t = 'n';
            else if (typeof cell.v === 'boolean') cell.t = 'b';
            else if (cell.v instanceof Date) {
                cell.t = 'n';
                cell.z = XLSX.SSF._table[14];
                cell.v = datenum(cell.v);
            } else cell.t = 's';

            ws[cell_ref] = cell;
        }
    }
    if (range.s.c < 10000000) ws['!ref'] = XLSX.utils.encode_range(range);
    return ws;
}

function Workbook() {
    if (!(this instanceof Workbook)) return new Workbook();
    this.SheetNames = [];
    this.Sheets = {};
}

function s2ab(s) {
    let buf = new ArrayBuffer(s.length);
    let view = new Uint8Array(buf);
    for (let i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xFF;
    return buf;
}

export default {
    export_table_to_excel(id) {
        let theTable = document.getElementById(id);
        let oo = generateArray(theTable);
        let ranges = oo[1];

        /* original data */
        let data = oo[0];
        let ws_name = "SheetJS";

        let wb = new Workbook(), ws = sheet_from_array_of_arrays(data);

        /* add ranges to worksheet */
        // ws['!cols'] = ['apple', 'banan'];
        ws['!merges'] = ranges;

        /* add worksheet to workbook */
        wb.SheetNames.push(ws_name);
        wb.Sheets[ws_name] = ws;

        let wbout = XLSX.write(wb, {bookType: 'xlsx', bookSST: false, type: 'binary'});

        FileSaver.saveAs(new Blob([s2ab(wbout)], {type: "application/octet-stream"}), "test.xlsx")
    },


    export_json_to_excel(th, jsonData, defaultTitle) {

        /* original data */

        let data = jsonData;
        data.unshift(th);
        let ws_name = "SheetJS";

        let wb = new Workbook(), ws = sheet_from_array_of_arrays(data);
        /*设置worksheet每列的最大宽度*/
        const colWidth = data.map(row => row.map(val => {
            /*先判断是否为null/undefined*/
            if (val == null) {
                return {'wch': 10};
            }
            /*再判断是否为中文*/
            else if (val.toString().charCodeAt(0) > 255) {
                return {'wch': val.toString().length * 2 + 5};
            } else {
                return {'wch': val.toString().length + 5};
            }
        }))
        /*以第一行为初始值*/
        let result = colWidth[0];
        for (let i = 1; i < colWidth.length; i++) {
            for (let j = 0; j < colWidth[i].length; j++) {
                if (result[j]['wch'] < colWidth[i][j]['wch']) {
                    result[j]['wch'] = colWidth[i][j]['wch'];
                }
            }
        }
        ws['!cols'] = result;

        /* add worksheet to workbook */
        wb.SheetNames.push(ws_name);
        wb.Sheets[ws_name] = ws;

        let wbout = XLSX.write(wb, {bookType: 'xlsx', bookSST: false, type: 'binary'});
        let title = defaultTitle || '列表'
        FileSaver.saveAs(new Blob([s2ab(wbout)], {type: "application/octet-stream"}), title + ".xlsx")
    }

}


